import sys

# for line in sys.stdin:
#     l = line.split()
#     print(int(l[0]) + int(l[1]))


#coding=utf-8
# 本题为考试多行输入输出规范示例，无需提交，不计分。
# import sys
# if __name__ == "__main__":
#     # 读取第一行的n
#     n = int(sys.stdin.readline().strip())
#     ans = 0
#     for i in range(n):
#         # 读取每一行
#         line = sys.stdin.readline().strip()
#         # 把每一行的数字分隔后转化成int列表
#         values = list(map(int, line.split()))
#         for v in values:
#             ans += v
#     print(ans)


def remove_duplicate(string):
    table = dict()
    
    res = ""
    for c in string:
        if c in table:
            continue
        res += c
        table[c] = 1
    return res

# for line in sys.stdin:
#     print(remove_duplicate(line))

print(remove_duplicate("12ere2"))
